title: Colloidal dispersions of monodisperse magnetite nanoparticles modified with poly(ethylene glycol).
abstract: Monodisperse magnetite nanoparticles modified with poly(ethylene glycol) (PEG) were synthesized using a silane functionalized PEG obtained by reacting 3-aminopropyl triethoxysilane with carboxylic acid-methoxy PEG (mPEG-COOH) using amide reactions. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential measurements show the particles are monodisperse (sigma(gv) approximately 0.2) and stable in water for pH of 3-9 and ionic strengths, up to 0.3 M NaCl. Thermogravimetric analysis coupled with TEM and DLS indicates formation of a dense graft layer on the particle surface. An analysis of the interparticle interaction energy indicates that the particles are stabilized by strong steric repulsions between PEG chains on their surface.
authors.affiliation: Department of Chemical Engineering, University of Puerto Rico, Mayagüez, PO Box 9046, Mayagüez, Puerto Rico.
authors.forename: Carola
authors.initials: C
authors.lastname: Barrera
authors.forename: Adriana P
authors.initials: AP
authors.lastname: Herrera
authors.forename: Carlos
authors.initials: C
authors.lastname: Rinaldi
mesh_terms: D003102:Colloids / Q000737:chemistry; D052203:Ferrosoferric Oxide / Q000138:chemical synthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D012821:Silanes / Q000138:chemical synthesis* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003102:Colloids; D012821:Silanes; D011092:Polyethylene Glycols; D052203:Ferrosoferric Oxide